1. Fields of the Invention
The present invention relates to a hidden roller of a treadmill, and more particularly, to a device which ensures the operation safety and achieves the practicalness.
2. Description of the Prior Art
Rollers fitted at the bottom of treadmills are used to facilitate a smooth movement of the treadmill, thereby achieving the laborsaving effect. A typical product is disclosed in U.S. Pat. No. 5,672,140 that describes roller sets are axially and pivotably arranged at one end of the ground-touching cross bars at both sides of the bottom of the treadmill while the roller sets in storage position are not in contact with the ground. In use, the roller sets are used as a pivoting point to incline the main body of the treadmill so as to facilitate the movement of the treadmill. Although this prior art can exactly reach the expected effect, it""s difficult for weak people to incline the heavy treadmill during its whole movement. Even, this could lead to an unnecessary accident.
Besides, the design of four rollers directly and permanently in contact with the ground can be seen in U.S. Pat. No. 5,372,559. However, this kind of structure will cause an unexpected sliding or shaking when the treadmill is operated. As a result, the safety of the user is seriously affected and it gradually becomes extinct on the market.
In order to effectively resolve the above-mentioned problems, a support member is provided at proper position of the roller set so as to increase the frictional resistance with the ground. This structure is disclosed in U.S. Pat. No. 6,090,016. However, a swinging see-saw effect will be created when the treadmill is moved on an uneven surface, thereby leading to inconvenience and difficulty of the horizontal adjustment.
In consideration of the above-mentioned, the inventor of the present invention thinks that the displacement of the treadmill is not a regular action. In operational position, it""s not required to use the roller sets. In storage position, it""s not necessarily required to shift the treadmill. As a result, partial roller sets can be stored and kept away from the ground so as to eliminate the unexpected sliding shift. In brief, all rollers are pulled out only when it""s really required to displace the treadmill. It is a primary object of the present invention to provide a hidden roller of a treadmill that is arranged in the hollow upright support so as to eliminate the above-mentioned drawbacks.